night vs dark

night and dark both are nouns.

Word	Noun	Adjective	Verb	Adverb
night	Yes	No	No	No
dark	Yes	Yes	No	No

As nouns, dark is a hypernym of night; that is, dark is a word with a broader meaning than night:

Other hypernyms of night include darkness.

As nouns, night and dark are synonyms defined as:

night and dark: the time after sunset and before sunrise while it is dark outside

Other synonyms of night include nighttime.

night (noun)	dark (noun)
darkness	an unenlightened state
the time after sunset and before sunrise while it is dark outside	an unilluminated area
a period of ignorance or backwardness or gloom	absence of light or illumination
the dark part of the diurnal cycle considered a time unit	absence of moral or spiritual values
the time between sunset and midnight	the time after sunset and before sunrise while it is dark outside
the period spent sleeping
a shortening of nightfall

night (adjective)	dark (adjective)
	devoid of or deficient in light or brightness; shadowed or black
	(used of color) having a dark hue
	brunet (used of hair or skin or eyes)
	secret
	causing dejection
	stemming from evil characteristics or forces; wicked or dishonorable
	showing a brooding ill humor
	not giving performances; closed
	marked by difficulty of style or expression
	lacking enlightenment or knowledge or culture